Abstract
Twenty activated sludge samples were collected from 15 wastewater treatment plants in 4 prefectures (Hokkaido, Saitama, Tokyo, and Okinawa) in each season throughout 1 year. They were analyzed by Fluorescence in situ Hybridization (FISH) technique with 6 oligonucleotide probes (targeted for Proteobacteria α-, β-, γ-subclasses, Gram positive high G+C content group, Cytophaga-Flavobacterium, and Eubacteria), and image analysis using confocal laser scanning microscope (CLSM). Experimental results showed that: In every season Proteobacteria was predominant in more than half samples and among Proteobacteria, α- and β-subclasses were predominant in almost all samples. Any clear relation between bacterial community and geographical condition or treatment method was not observed. Either, any clear correlation between water qualities and bacterial population was not observed. But some seasonal change was remarkable; increase of α-subclass from winter to summer and decrease from summer to winter, and the opposite tendency of HGC group.
